Overview

Functions

It contains numerous baroreceptors, which function as a "sampling area" for many homeostatic mechanisms for maintaining blood pressure. The carotid sinus baroreceptors are innervated by the sinus nerve of Hering, which is a branch of IX (glossopharyngeal nerve). The glossopharyngeal nerve synapses in the nucleus tractus solitarius (NTS) located in the medulla of the brainstem. The NTS modulates the activity of sympathetic and parasympathetic (vagal) neurons in the medulla. These neurons then regulate the autonomic control of the heart and blood vessels. The aortic arch baroreceptors are innervated by the aortic nerve, which combines with X (vagus nerve) and travels to the NTS.

The carotid sinus can be oversensitive to manual stimulation, a condition known as carotid sinus hypersensitivity, carotid sinus syndrome or carotid sinus syncope, in which manual stimulation causes large changes in heart rate and/or blood pressure.

Carotid sinus reflex death

Carotid sinus reflex death is a disputed mechanism of death in which manual stimulation of the carotid sinus allegedly causes strong vagus nerve impulses leading to terminal cardiac arrest. Carotid sinus reflex death has been pointed out as a possible cause of death in cases of strangulation and hanging, but such deductions remain controversial. Studies have however suggested that the carotid sinus reflex can be a contributing factor in other mechanisms of death by reducing blood pressure and heart rate, especially in the elderly or in people suffering from carotid sinus hypersensitivity. A Carotid Massage can also possibly dislodge a thrombus, or some plaque. This could lead to any number of life threatening effects, including, but not limited to; Pulmonary Embolus, Myocardial Infarctions, and Strokes. All of these are potentially lethal. [4]